System and method for scheduled snapshot pacing with deduplication

ABSTRACT

A method, computer program product, and computer system for submitting, by a computing device, at least one snapshot request of a plurality of snapshots requests into a snapshot queue. How many snapshots of a plurality of snapshots are referencing a given point in time copy may be tracked, wherein the given point in time copy may be mapped to at least a portion of the plurality of snapshots. A desired executing time for the at least one snapshot request in the snapshot queue may be determined. The at least one snapshot request may be dequeued.

BACKGROUND

Scheduled snapshot operations for volumes, volume groups, file systems,VMware virtual volumes, etc. may be an important feature of dataprotection for both on-premise and cloud-based storage solutions.Scheduled snapshots may be created using snapshot rules. A snapshot rulegenerally may identify how frequently a snapshot needs to be taken andhow long it needs to be retained. Multiple snapshot rules are typicallygrouped together into a protection policy, and the policy maypotentially be assigned to thousands of storage objects (e.g., volume,file system, etc.). These independent snapshot rules may potentiallyexecute at the same time against a large number of objects resulting ina surge of snapshot requests.

BRIEF SUMMARY OF DISCLOSURE

In one example implementation, a method, performed by one or morecomputing devices, may include but is not limited to submitting, by acomputing device, at least one snapshot request of a plurality ofsnapshots requests into a snapshot queue. How many snapshots of aplurality of snapshots are referencing a given point in time copy may betracked, wherein the given point in time copy may be mapped to at leasta portion of the plurality of snapshots. A desired executing time forthe at least one snapshot request in the snapshot queue may bedetermined. The at least one snapshot request may be dequeued.

One or more of the following example features may be included. Thedequeuing may be based upon, at least in part, a centralized timer.Duplicate requests in the snapshot queue may be deduplicated. Thedequeuing may be based upon, at least in part, at least one of anexecuting time of the at least one request being less than or equal to acurrent time and a duplicate request for a same storage object. Thedesired execution time may be based upon, at least in part, a storageobject ID and a pacing window. An entry of the at least one snapshotrequest may be deleted. A reference count may be decremented from areference count table.

In another example implementation, a computing system may include one ormore processors and one or more memories configured to performoperations that may include but are not limited to submitting at leastone snapshot request of a plurality of snapshots requests into asnapshot queue. How many snapshots of a plurality of snapshots arereferencing a given point in time copy may be tracked, wherein the givenpoint in time copy may be mapped to at least a portion of the pluralityof snapshots. A desired executing time for the at least one snapshotrequest in the snapshot queue may be determined. The at least onesnapshot request may be dequeued.

One or more of the following example features may be included. Thedequeuing may be based upon, at least in part, a centralized timer.Duplicate requests in the snapshot queue may be deduplicated. Thedequeuing may be based upon, at least in part, at least one of anexecuting time of the at least one request being less than or equal to acurrent time and a duplicate request for a same storage object. Thedesired execution time may be based upon, at least in part, a storageobject ID and a pacing window. An entry of the at least one snapshotrequest may be deleted. A reference count may be decremented from areference count table.

In another example implementation, a computer program product may resideon a computer readable storage medium having a plurality of instructionsstored thereon which, when executed across one or more processors, maycause at least a portion of the one or more processors to performoperations that may include but are not limited to submitting at leastone snapshot request of a plurality of snapshots requests into asnapshot queue. How many snapshots of a plurality of snapshots arereferencing a given point in time copy may be tracked, wherein the givenpoint in time copy may be mapped to at least a portion of the pluralityof snapshots. A desired executing time for the at least one snapshotrequest in the snapshot queue may be determined. The at least onesnapshot request may be dequeued.

One or more of the following example features may be included. Thedequeuing may be based upon, at least in part, a centralized timer.Duplicate requests in the snapshot queue may be deduplicated. Thedequeuing may be based upon, at least in part, at least one of anexecuting time of the at least one request being less than or equal to acurrent time and a duplicate request for a same storage object. Thedesired execution time may be based upon, at least in part, a storageobject ID and a pacing window. An entry of the at least one snapshotrequest may be deleted. A reference count may be decremented from areference count table.

The details of one or more example implementations are set forth in theaccompanying drawings and the description below. Other possible examplefeatures and/or possible example advantages will become apparent fromthe description, the drawings, and the claims. Some implementations maynot have those possible example features and/or possible exampleadvantages, and such possible example features and/or possible exampleadvantages may not necessarily be required of some implementations.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an example diagrammatic view of a copy process coupled to anexample distributed computing network according to one or more exampleimplementations of the disclosure;

FIG. 2 is an example diagrammatic view of a storage system of FIG. 1according to one or more example implementations of the disclosure;

FIG. 3 is an example diagrammatic view of a storage target of FIG. 1according to one or more example implementations of the disclosure;

FIG. 4 is an example flowchart of a copy process according to one ormore example implementations of the disclosure;

FIG. 5 is an example diagrammatic view of a snapshot request queueaccording to one or more example implementations of the disclosure;

FIG. 6 is an example diagrammatic view of a PIT copy reference counttable entry according to one or more example implementations of thedisclosure; and

FIG. 7 is an example flowchart of a dequeuing/deduplication process of acopy process according to one or more example implementations of thedisclosure.

Like reference symbols in the various drawings indicate like elements.

DETAILED DESCRIPTION

System Overview:

In some implementations, the present disclosure may be embodied as amethod, system, or computer program product. Accordingly, in someimplementations, the present disclosure may take the form of an entirelyhardware implementation, an entirely software implementation (includingfirmware, resident software, micro-code, etc.) or an implementationcombining software and hardware aspects that may all generally bereferred to herein as a “circuit,” “module” or “system.” Furthermore, insome implementations, the present disclosure may take the form of acomputer program product on a computer-usable storage medium havingcomputer-usable program code embodied in the medium.

In some implementations, any suitable computer usable or computerreadable medium (or media) may be utilized. The computer readable mediummay be a computer readable signal medium or a computer readable storagemedium. The computer-usable, or computer-readable, storage medium(including a storage device associated with a computing device or clientelectronic device) may be, for example, but is not limited to, anelectronic, magnetic, optical, electromagnetic, infrared, orsemiconductor system, apparatus, device, or any suitable combination ofthe foregoing. More specific examples (a non-exhaustive list) of thecomputer-readable medium may include the following: an electricalconnection having one or more wires, a portable computer diskette, ahard disk, a random access memory (RAM), a read-only memory (ROM), anerasable programmable read-only memory (EPROM or Flash memory), anoptical fiber, a portable compact disc read-only memory (CD-ROM), anoptical storage device, a digital versatile disk (DVD), a static randomaccess memory (SRAM), a memory stick, a floppy disk, a mechanicallyencoded device such as punch-cards or raised structures in a groovehaving instructions recorded thereon, a media such as those supportingthe internet or an intranet, or a magnetic storage device. Note that thecomputer-usable or computer-readable medium could even be a suitablemedium upon which the program is stored, scanned, compiled, interpreted,or otherwise processed in a suitable manner, if necessary, and thenstored in a computer memory. In the context of the present disclosure, acomputer-usable or computer-readable, storage medium may be any tangiblemedium that can contain or store a program for use by or in connectionwith the instruction execution system, apparatus, or device.

In some implementations, a computer readable signal medium may include apropagated data signal with computer readable program code embodiedtherein, for example, in baseband or as part of a carrier wave. In someimplementations, such a propagated signal may take any of a variety offorms, including, but not limited to, electro-magnetic, optical, or anysuitable combination thereof. In some implementations, the computerreadable program code may be transmitted using any appropriate medium,including but not limited to the internet, wireline, optical fibercable, RF, etc. In some implementations, a computer readable signalmedium may be any computer readable medium that is not a computerreadable storage medium and that can communicate, propagate, ortransport a program for use by or in connection with an instructionexecution system, apparatus, or device.

In some implementations, computer program code for carrying outoperations of the present disclosure may be assembler instructions,instruction-set-architecture (ISA) instructions, machine instructions,machine dependent instructions, microcode, firmware instructions,state-setting data, or either source code or object code written in anycombination of one or more programming languages, including an objectoriented programming language such as Java®, Smalltalk, C++ or the like.Java® and all Java-based trademarks and logos are trademarks orregistered trademarks of Oracle and/or its affiliates. However, thecomputer program code for carrying out operations of the presentdisclosure may also be written in conventional procedural programminglanguages, such as the “C” programming language, PASCAL, or similarprogramming languages, as well as in scripting languages such asJavascript, PERL, or Python. The program code may execute entirely onthe user's computer, partly on the user's computer, as a stand-alonesoftware package, partly on the user's computer and partly on a remotecomputer or entirely on the remote computer or server. In the latterscenario, the remote computer may be connected to the user's computerthrough a local area network (LAN) or a wide area network (WAN), or theconnection may be made to an external computer (for example, through theinternet using an Internet Service Provider). In some implementations,electronic circuitry including, for example, programmable logiccircuitry, field-programmable gate arrays (FPGAs) or other hardwareaccelerators, micro-controller units (MCUs), or programmable logicarrays (PLAs) may execute the computer readable programinstructions/code by utilizing state information of the computerreadable program instructions to personalize the electronic circuitry,in order to perform aspects of the present disclosure.

In some implementations, the flowchart and block diagrams in the figuresillustrate the architecture, functionality, and operation of possibleimplementations of apparatus (systems), methods and computer programproducts according to various implementations of the present disclosure.Each block in the flowchart and/or block diagrams, and combinations ofblocks in the flowchart and/or block diagrams, may represent a module,segment, or portion of code, which comprises one or more executablecomputer program instructions for implementing the specified logicalfunction(s)/act(s). These computer program instructions may be providedto a processor of a general purpose computer, special purpose computer,or other programmable data processing apparatus to produce a machine,such that the computer program instructions, which may execute via theprocessor of the computer or other programmable data processingapparatus, create the ability to implement one or more of thefunctions/acts specified in the flowchart and/or block diagram block orblocks or combinations thereof. It should be noted that, in someimplementations, the functions noted in the block(s) may occur out ofthe order noted in the figures (or combined or omitted). For example,two blocks shown in succession may, in fact, be executed substantiallyconcurrently, or the blocks may sometimes be executed in the reverseorder, depending upon the functionality involved.

In some implementations, these computer program instructions may also bestored in a computer-readable memory that can direct a computer or otherprogrammable data processing apparatus to function in a particularmanner, such that the instructions stored in the computer-readablememory produce an article of manufacture including instruction meanswhich implement the function/act specified in the flowchart and/or blockdiagram block or blocks or combinations thereof.

In some implementations, the computer program instructions may also beloaded onto a computer or other programmable data processing apparatusto cause a series of operational steps to be performed (not necessarilyin a particular order) on the computer or other programmable apparatusto produce a computer implemented process such that the instructionswhich execute on the computer or other programmable apparatus providesteps for implementing the functions/acts (not necessarily in aparticular order) specified in the flowchart and/or block diagram blockor blocks or combinations thereof.

Referring now to the example implementation of FIG. 1, there is showncopy process 10 that may reside on and may be executed by a computer(e.g., computer 12), which may be connected to a network (e.g., network14) (e.g., the internet or a local area network). Examples of computer12 (and/or one or more of the client electronic devices noted below) mayinclude, but are not limited to, a storage system (e.g., a NetworkAttached Storage (NAS) system, a Storage Area Network (SAN)), a personalcomputer(s), a laptop computer(s), mobile computing device(s), a servercomputer, a series of server computers, a mainframe computer(s), or acomputing cloud(s). As is known in the art, a SAN may include one ormore of the client electronic devices, including a RAID device and a NASsystem. In some implementations, each of the aforementioned may begenerally described as a computing device. In certain implementations, acomputing device may be a physical or virtual device. In manyimplementations, a computing device may be any device capable ofperforming operations, such as a dedicated processor, a portion of aprocessor, a virtual processor, a portion of a virtual processor,portion of a virtual device, or a virtual device. In someimplementations, a processor may be a physical processor or a virtualprocessor. In some implementations, a virtual processor may correspondto one or more parts of one or more physical processors. In someimplementations, the instructions/logic may be distributed and executedacross one or more processors, virtual or physical, to execute theinstructions/logic. Computer 12 may execute an operating system, forexample, but not limited to, Microsoft® Windows®; Mac® OS X®; Red Hat®Linux®, Windows® Mobile, Chrome OS, Blackberry OS, Fire OS, or a customoperating system. (Microsoft and Windows are registered trademarks ofMicrosoft Corporation in the United States, other countries or both; Macand OS X are registered trademarks of Apple Inc. in the United States,other countries or both; Red Hat is a registered trademark of Red HatCorporation in the United States, other countries or both; and Linux isa registered trademark of Linus Torvalds in the United States, othercountries or both).

In some implementations, as will be discussed below in greater detail, acopy process, such as copy process 10 of FIG. 1, may submit, by acomputing device, at least one snapshot request of a plurality ofsnapshots requests into a snapshot queue. How many snapshots of aplurality of snapshots are referencing a given point in time copy may betracked, wherein the given point in time copy may be mapped to at leasta portion of the plurality of snapshots. A desired executing time forthe at least one snapshot request in the snapshot queue may bedetermined. The at least one snapshot request may be dequeued.

In some implementations, the instruction sets and subroutines of copyprocess 10, which may be stored on storage device, such as storagedevice 16, coupled to computer 12, may be executed by one or moreprocessors and one or more memory architectures included within computer12. In some implementations, storage device 16 may include but is notlimited to: a hard disk drive; all forms of flash memory storagedevices; a tape drive; an optical drive; a RAID array (or other array);a random access memory (RAM); a read-only memory (ROM); or combinationthereof. In some implementations, storage device 16 may be organized asan extent, an extent pool, a RAID extent (e.g., an example 4D+1P R5,where the RAID extent may include, e.g., five storage device extentsthat may be allocated from, e.g., five different storage devices), amapped RAID (e.g., a collection of RAID extents), or combinationthereof.

In some implementations, network 14 may be connected to one or moresecondary networks (e.g., network 18), examples of which may include butare not limited to: a local area network; a wide area network or othertelecommunications network facility; or an intranet, for example. Thephrase “telecommunications network facility,” as used herein, may referto a facility configured to transmit, and/or receive transmissionsto/from one or more mobile client electronic devices (e.g., cellphones,etc.) as well as many others.

In some implementations, computer 12 may include a data store, such as adatabase (e.g., relational database, object-oriented database,triplestore database, etc.) and may be located within any suitablememory location, such as storage device 16 coupled to computer 12. Insome implementations, data, metadata, information, etc. describedthroughout the present disclosure may be stored in the data store. Insome implementations, computer 12 may utilize any known databasemanagement system such as, but not limited to, DB2, in order to providemulti-user access to one or more databases, such as the above notedrelational database. In some implementations, the data store may also bea custom database, such as, for example, a flat file database or an XMLdatabase. In some implementations, any other form(s) of a data storagestructure and/or organization may also be used. In some implementations,copy process 10 may be a component of the data store, a standaloneapplication that interfaces with the above noted data store and/or anapplet/application that is accessed via client applications 22, 24, 26,28. In some implementations, the above noted data store may be, in wholeor in part, distributed in a cloud computing topology. In this way,computer 12 and storage device 16 may refer to multiple devices, whichmay also be distributed throughout the network.

In some implementations, computer 12 may execute a storage managementapplication (e.g., storage management application 21), examples of whichmay include, but are not limited to, e.g., a storage system application,a cloud computing application, a data synchronization application, adata migration application, a garbage collection application, or otherapplication that allows for the implementation and/or management of datain a clustered (or non-clustered) environment (or the like). In someimplementations, copy process 10 and/or storage management application21 may be accessed via one or more of client applications 22, 24, 26,28. In some implementations, copy process 10 may be a standaloneapplication, or may be an applet/application/script/extension that mayinteract with and/or be executed within storage management application21, a component of storage management application 21, and/or one or moreof client applications 22, 24, 26, 28. In some implementations, storagemanagement application 21 may be a standalone application, or may be anapplet/application/script/extension that may interact with and/or beexecuted within copy process 10, a component of copy process 10, and/orone or more of client applications 22, 24, 26, 28. In someimplementations, one or more of client applications 22, 24, 26, 28 maybe a standalone application, or may be anapplet/application/script/extension that may interact with and/or beexecuted within and/or be a component of copy process 10 and/or storagemanagement application 21. Examples of client applications 22, 24, 26,28 may include, but are not limited to, e.g., a storage systemapplication, a cloud computing application, a data synchronizationapplication, a data migration application, a garbage collectionapplication, or other application that allows for the implementationand/or management of data in a clustered (or non-clustered) environment(or the like), a standard and/or mobile web browser, an emailapplication (e.g., an email client application), a textual and/or agraphical user interface, a customized web browser, a plugin, anApplication Programming Interface (API), or a custom application. Theinstruction sets and subroutines of client applications 22, 24, 26, 28,which may be stored on storage devices 30, 32, 34, 36, coupled to clientelectronic devices 38, 40, 42, 44, may be executed by one or moreprocessors and one or more memory architectures incorporated into clientelectronic devices 38, 40, 42, 44.

In some implementations, one or more of storage devices 30, 32, 34, 36,may include but are not limited to: hard disk drives; flash drives, tapedrives; optical drives; RAID arrays; random access memories (RAM); andread-only memories (ROM). Examples of client electronic devices 38, 40,42, 44 (and/or computer 12) may include, but are not limited to, apersonal computer (e.g., client electronic device 38), a laptop computer(e.g., client electronic device 40), a smart/data-enabled, cellularphone (e.g., client electronic device 42), a notebook computer (e.g.,client electronic device 44), a tablet, a server, a television, a smarttelevision, a smart speaker, an Internet of Things (IoT) device, a media(e.g., video, photo, etc.) capturing device, and a dedicated networkdevice. Client electronic devices 38, 40, 42, 44 may each execute anoperating system, examples of which may include but are not limited to,Android™, Apple® iOS®, Mac® OS X®; Red Hat® Linux®, Windows® Mobile,Chrome OS, Blackberry OS, Fire OS, or a custom operating system.

In some implementations, one or more of client applications 22, 24, 26,28 may be configured to effectuate some or all of the functionality ofcopy process 10 (and vice versa). Accordingly, in some implementations,copy process 10 may be a purely server-side application, a purelyclient-side application, or a hybrid server-side/client-side applicationthat is cooperatively executed by one or more of client applications 22,24, 26, 28 and/or copy process 10.

In some implementations, one or more of client applications 22, 24, 26,28 may be configured to effectuate some or all of the functionality ofstorage management application 21 (and vice versa). Accordingly, in someimplementations, storage management application 21 may be a purelyserver-side application, a purely client-side application, or a hybridserver-side/client-side application that is cooperatively executed byone or more of client applications 22, 24, 26, 28 and/or storagemanagement application 21. As one or more of client applications 22, 24,26, 28, copy process 10, and storage management application 21, takensingly or in any combination, may effectuate some or all of the samefunctionality, any description of effectuating such functionality viaone or more of client applications 22, 24, 26, 28, copy process 10,storage management application 21, or combination thereof, and anydescribed interaction(s) between one or more of client applications 22,24, 26, 28, copy process 10, storage management application 21, orcombination thereof to effectuate such functionality, should be taken asan example only and not to limit the scope of the disclosure.

In some implementations, one or more of users 46, 48, 50, 52 may accesscomputer 12 and copy process 10 (e.g., using one or more of clientelectronic devices 38, 40, 42, 44) directly through network 14 orthrough secondary network 18. Further, computer 12 may be connected tonetwork 14 through secondary network 18, as illustrated with phantomlink line 54. Copy process 10 may include one or more user interfaces,such as browsers and textual or graphical user interfaces, through whichusers 46, 48, 50, 52 may access copy process 10.

In some implementations, the various client electronic devices may bedirectly or indirectly coupled to network 14 (or network 18). Forexample, client electronic device 38 is shown directly coupled tonetwork 14 via a hardwired network connection. Further, clientelectronic device 44 is shown directly coupled to network 18 via ahardwired network connection. Client electronic device 40 is shownwirelessly coupled to network 14 via wireless communication channel 56established between client electronic device 40 and wireless accesspoint (i.e., WAP) 58, which is shown directly coupled to network 14. WAP58 may be, for example, an IEEE 802.11a, 802.11b, 802.11g, 802.11n,802.11ac, Wi-Fi®, RFID, and/or Bluetooth™ (including Bluetooth™ LowEnergy) device that is capable of establishing wireless communicationchannel 56 between client electronic device 40 and WAP 58. Clientelectronic device 42 is shown wirelessly coupled to network 14 viawireless communication channel 60 established between client electronicdevice 42 and cellular network/bridge 62, which is shown by exampledirectly coupled to network 14.

In some implementations, some or all of the IEEE 802.11x specificationsmay use Ethernet protocol and carrier sense multiple access withcollision avoidance (i.e., CSMA/CA) for path sharing. The various802.11x specifications may use phase-shift keying (i.e., PSK) modulationor complementary code keying (i.e., CCK) modulation, for example.Bluetooth™ (including Bluetooth™ Low Energy) is a telecommunicationsindustry specification that allows, e.g., mobile phones, computers,smart phones, and other electronic devices to be interconnected using ashort-range wireless connection. Other forms of interconnection (e.g.,Near Field Communication (NFC)) may also be used.

In some implementations, various I/O requests (e.g., I/O request 15) maybe sent from, e.g., client applications 22, 24, 26, 28 to, e.g.,computer 12. Examples of I/O request 15 may include but are not limitedto, data write requests (e.g., a request that content be written tocomputer 12) and data read requests (e.g., a request that content beread from computer 12).

Data Storage System:

Referring also to the example implementation of FIGS. 2-3 (e.g., wherecomputer 12 may be configured as a data storage system), computer 12 mayinclude storage processor 100 and a plurality of storage targets (e.g.,storage targets 102, 104, 106, 108, 110). In some implementations,storage targets 102, 104, 106, 108, 110 may include any of theabove-noted storage devices. In some implementations, storage targets102, 104, 106, 108, 110 may be configured to provide various levels ofperformance and/or high availability. For example, storage targets 102,104, 106, 108, 110 may be configured to form a non-fully-duplicativefault-tolerant data storage system (such as a non-fully-duplicative RAIDdata storage system), examples of which may include but are not limitedto: RAID 3 arrays, RAID 4 arrays, RAID 5 arrays, and/or RAID 6 arrays.It will be appreciated that various other types of RAID arrays may beused without departing from the scope of the present disclosure.

While in this particular example, computer 12 is shown to include fivestorage targets (e.g., storage targets 102, 104, 106, 108, 110), this isfor example purposes only and is not intended limit the presentdisclosure. For instance, the actual number of storage targets may beincreased or decreased depending upon, e.g., the level ofredundancy/performance/capacity required.

Further, the storage targets (e.g., storage targets 102, 104, 106, 108,110) included with computer 12 may be configured to form a plurality ofdiscrete storage arrays. For instance, and assuming for example purposesonly that computer 12 includes, e.g., ten discrete storage targets, afirst five targets (of the ten storage targets) may be configured toform a first RAID array and a second five targets (of the ten storagetargets) may be configured to form a second RAID array.

In some implementations, one or more of storage targets 102, 104, 106,108, 110 may be configured to store coded data (e.g., via storagemanagement process 21), wherein such coded data may allow for theregeneration of data lost/corrupted on one or more of storage targets102, 104, 106, 108, 110. Examples of such coded data may include but isnot limited to parity data and Reed-Solomon data. Such coded data may bedistributed across all of storage targets 102, 104, 106, 108, 110 or maybe stored within a specific storage target.

Examples of storage targets 102, 104, 106, 108, 110 may include one ormore data arrays, wherein a combination of storage targets 102, 104,106, 108, 110 (and any processing/control systems associated withstorage management application 21) may form data array 112.

The manner in which computer 12 is implemented may vary depending upone.g., the level of redundancy/performance/capacity required. Forexample, computer 12 may be configured as a SAN (i.e., a Storage AreaNetwork), in which storage processor 100 may be, e.g., a dedicatedcomputing system and each of storage targets 102, 104, 106, 108, 110 maybe a RAID device. An example of storage processor 100 may include but isnot limited to a VPLEX™, VNX™, TRIDENT™, or Unity™ system offered byDell EMC™ of Hopkinton, Mass.

In the example where computer 12 is configured as a SAN, the variouscomponents of computer 12 (e.g., storage processor 100, and storagetargets 102, 104, 106, 108, 110) may be coupled using networkinfrastructure 114, examples of which may include but are not limited toan Ethernet (e.g., Layer 2 or Layer 3) network, a fiber channel network,an InfiniB and network, or any other circuit switched/packet switchednetwork.

As discussed above, various I/O requests (e.g., I/O request 15) may begenerated. For example, these I/O requests may be sent from, e.g.,client applications 22, 24, 26, 28 to, e.g., computer 12.Additionally/alternatively (e.g., when storage processor 100 isconfigured as an application server or otherwise), these I/O requestsmay be internally generated within storage processor 100 (e.g., viastorage management process 21). Examples of I/O request 15 may includebut are not limited to data write request 116 (e.g., a request thatcontent 118 be written to computer 12) and data read request 120 (e.g.,a request that content 118 be read from computer 12).

In some implementations, during operation of storage processor 100,content 118 to be written to computer 12 may be received and/orprocessed by storage processor 100 (e.g., via storage management process21). Additionally/alternatively (e.g., when storage processor 100 isconfigured as an application server or otherwise), content 118 to bewritten to computer 12 may be internally generated by storage processor100 (e.g., via storage management process 21).

As discussed above, the instruction sets and subroutines of storagemanagement application 21, which may be stored on storage device 16included within computer 12, may be executed by one or more processorsand one or more memory architectures included with computer 12.Accordingly, in addition to being executed on storage processor 100,some or all of the instruction sets and subroutines of storagemanagement application 21 (and/or copy process 10) may be executed byone or more processors and one or more memory architectures includedwith data array 112.

In some implementations, storage processor 100 may include front endcache memory system 122. Examples of front end cache memory system 122may include but are not limited to a volatile, solid-state, cache memorysystem (e.g., a dynamic RAM cache memory system), a non-volatile,solid-state, cache memory system (e.g., a flash-based, cache memorysystem), and/or any of the above-noted storage devices.

In some implementations, storage processor 100 may initially storecontent 118 within front end cache memory system 122. Depending upon themanner in which front end cache memory system 122 is configured, storageprocessor 100 (e.g., via storage management process 21) may immediatelywrite content 118 to data array 112 (e.g., if front end cache memorysystem 122 is configured as a write-through cache) or may subsequentlywrite content 118 to data array 112 (e.g., if front end cache memorysystem 122 is configured as a write-back cache).

In some implementations, one or more of storage targets 102, 104, 106,108, 110 may include a backend cache memory system. Examples of thebackend cache memory system may include but are not limited to avolatile, solid-state, cache memory system (e.g., a dynamic RAM cachememory system), a non-volatile, solid-state, cache memory system (e.g.,a flash-based, cache memory system), and/or any of the above-notedstorage devices.

Storage Targets:

As discussed above, one or more of storage targets 102, 104, 106, 108,110 may be a RAID device. For instance, and referring also to FIG. 3,there is shown example target 150, wherein target 150 may be one exampleimplementation of a RAID implementation of, e.g., storage target 102,storage target 104, storage target 106, storage target 108, and/orstorage target 110. An example of target 150 may include but is notlimited to a VPLEX™, VNX™, TRIDENT™, or Unity™ system offered by DellEMC™ of Hopkinton, Mass. Examples of storage devices 154, 156, 158, 160,162 may include one or more electro-mechanical hard disk drives, one ormore solid-state/flash devices, and/or any of the above-noted storagedevices. It will be appreciated that while the term “disk” or “drive”may be used throughout, these may refer to and be used interchangeablywith any types of appropriate storage devices as the context andfunctionality of the storage device permits.

In some implementations, target 150 may include storage processor 152and a plurality of storage devices (e.g., storage devices 154, 156, 158,160, 162). Storage devices 154, 156, 158, 160, 162 may be configured toprovide various levels of performance and/or high availability (e.g.,via storage management process 21). For example, one or more of storagedevices 154, 156, 158, 160, 162 (or any of the above-noted storagedevices) may be configured as a RAID 0 array, in which data is stripedacross storage devices. By striping data across a plurality of storagedevices, improved performance may be realized. However, RAID 0 arraysmay not provide a level of high availability. Accordingly, one or moreof storage devices 154, 156, 158, 160, 162 (or any of the above-notedstorage devices) may be configured as a RAID 1 array, in which data ismirrored between storage devices. By mirroring data between storagedevices, a level of high availability may be achieved as multiple copiesof the data may be stored within storage devices 154, 156, 158, 160,162.

While storage devices 154, 156, 158, 160, 162 are discussed above asbeing configured in a RAID 0 or RAID 1 array, this is for examplepurposes only and not intended to limit the present disclosure, as otherconfigurations are possible. For example, storage devices 154, 156, 158,160, 162 may be configured as a RAID 3, RAID 4, RAID 5 or RAID 6 array.

While in this particular example, target 150 is shown to include fivestorage devices (e.g., storage devices 154, 156, 158, 160, 162), this isfor example purposes only and not intended to limit the presentdisclosure. For instance, the actual number of storage devices may beincreased or decreased depending upon, e.g., the level ofredundancy/performance/capacity required.

In some implementations, one or more of storage devices 154, 156, 158,160, 162 may be configured to store (e.g., via storage managementprocess 21) coded data, wherein such coded data may allow for theregeneration of data lost/corrupted on one or more of storage devices154, 156, 158, 160, 162. Examples of such coded data may include but arenot limited to parity data and Reed-Solomon data. Such coded data may bedistributed across all of storage devices 154, 156, 158, 160, 162 or maybe stored within a specific storage device.

The manner in which target 150 is implemented may vary depending upone.g., the level of redundancy/performance/capacity required. Forexample, target 150 may be a RAID device in which storage processor 152is a RAID controller card and storage devices 154, 156, 158, 160, 162are individual “hot-swappable” hard disk drives. Another example oftarget 150 may be a RAID system, examples of which may include but arenot limited to an NAS (i.e., Network Attached Storage) device or a SAN(i.e., Storage Area Network).

In some implementations, storage target 150 may execute all or a portionof storage management application 21. The instruction sets andsubroutines of storage management application 21, which may be stored ona storage device (e.g., storage device 164) coupled to storage processor152, may be executed by one or more processors and one or more memoryarchitectures included with storage processor 152. Storage device 164may include but is not limited to any of the above-noted storagedevices.

As discussed above, computer 12 may be configured as a SAN, whereinstorage processor 100 may be a dedicated computing system and each ofstorage targets 102, 104, 106, 108, 110 may be a RAID device.Accordingly, when storage processor 100 processes data requests 116,120, storage processor 100 (e.g., via storage management process 21) mayprovide the appropriate requests/content (e.g., write request 166,content 168 and read request 170) to, e.g., storage target 150 (which isrepresentative of storage targets 102, 104, 106, 108 and/or 110).

In some implementations, during operation of storage processor 152,content 168 to be written to target 150 may be processed by storageprocessor 152 (e.g., via storage management process 21). Storageprocessor 152 may include cache memory system 172. Examples of cachememory system 172 may include but are not limited to a volatile,solid-state, cache memory system (e.g., a dynamic RAM cache memorysystem) and/or a non-volatile, solid-state, cache memory system (e.g., aflash-based, cache memory system). During operation of storage processor152, content 168 to be written to target 150 may be received by storageprocessor 152 (e.g., via storage management process 21) and initiallystored (e.g., via storage management process 21) within front end cachememory system 172.

Scheduled snapshot operations for volumes, volume groups, file systems,VMware virtual volumes, etc. may be an important feature of dataprotection for both on-premise and cloud-based storage solutions.Scheduled snapshots may be created using snapshot rules. A snapshot rulegenerally may identify how frequently a snapshot needs to be taken andhow long it needs to be retained. Multiple snapshot rules are typicallygrouped together into a protection policy, and the policy maypotentially be assigned to thousands of storage objects (e.g., volume,file system, etc.). These independent snapshot rules may potentiallyexecute at the same time against a large number of objects resulting ina surge of snapshot requests. When taking a snapshot, ongoing host IOmay need to be momentarily quiesced. While individual snapshot requestsare designed to be minimally impactful to host TO, a surge of snapshotrequests across many objects at the same time may drag the overallsystem performance down resulting in spikes in system level latencyspikes.

The snapshot rules of a policy may also overlap at certain times of theday resulting in multiple concurrent snapshot requests against the sameobject at the same time. For example, if a protection policy has onesnapshot rule that executes every five minutes, one snapshot ruleexecutes every thirty minutes and another snapshot rule executes everyone hour, there may be three snapshot requests that create the threepoint-in-time (PIT) copies of the same data at the one hour mark sent todata path. Such multiple simultaneous snapshot requests on the sameobject may severely impact the performance of individual objects andexacerbate the latency spike at the system level.

Therefore, as will be discussed in greater detail below, the presentdisclosure may address the so-called “thundering herd” problem acrossthe two dimensions. For example, multiple snapshot requests originatingfrom a single rule may be spaced out across a relative time window byusing an object id-based hashing algorithm. For example, a five minutesnapshot rule applied to, e.g., 1000 objects would have previouslygenerated 1000 requests at the same time. With the present disclosure,the requests may be partitioned across the five minute window such thata subset of requests are executed at a specific time offset from thestart of this time window. Using an example hash on the object id mayensure the same offset is used for a given object every five minutes,thereby providing a consistent five minute differential betweenrequests.

Additionally, concurrent snapshot requests against the same object frommultiple rules may be deduplicated. Using a reference countingmechanism, a single PIT copy in data path may be associated withmultiple requests and presented as multiple snapshots to the user. Eachsuch deduplicated user-facing snapshot may have a distinct name andretention period. When the last of the deduplicated snapshots is deletedfrom the system, the actual PIT copy may be removed from the data path.Under the earlier example, at the top of an hour, the end user will seethree distinct snapshots, one for each snapshot rule. But there willonly be one request sent to data path to create a single PIT copy forall three snapshot rules. Both solutions may be incorporated into acommon procedure using a system managed snapshot request queue asoutlined below. For example purposes only, the present disclosure usesthe standalone volume snapshot which has a PIT copy in data path and anend-user-visible snapshot in control path. However, it will beappreciated that the same concept may be similarly applied to otherresource types as well.

The Copy Process:

As discussed above and referring also at least to the exampleimplementations of FIGS. 4-7, copy process 10 may submit 400, by acomputing device, at least one snapshot request of a plurality ofsnapshots requests into a snapshot queue. Copy process 10 may track 402how many snapshots of a plurality of snapshots are referencing a givenpoint in time copy. Copy process 10 may determine 404 a desiredexecuting time for the at least one snapshot request in the snapshotqueue. Copy process 10 may dequeue 406 the at least one snapshotrequest.

In some implementations, copy process 10 may submit 400, by a computingdevice, at least one snapshot request of a plurality of snapshotsrequests into a snapshot queue. For example, a snapshot request queuemay be introduced in control path, and a reference count may beintroduced in control path for a PIT copy created at data path. Thereference count may prevent the system managed PIT copy from beingdeleted until all the referenced snapshot instances are gone. In someimplementations, the snapshot creation requests coming from differentsnapshot rules may be placed in the snapshot queue with a desiredexecution time. When a snapshot request is triggered from a rule, therequest will be submitted to the snapshot request queue. The persistentsnapshot request queue 500 (shown in the example implementation of FIG.5) may have the following example and non-limiting attributes:

-   -   id: The unique id of the snapshot request    -   storage_object_id: The globally unique id of the storage object.    -   execution_time: The computed execution time of the request        (discussed further below).    -   snapshot_attributes: Additional attributes that may be needed to        fulfill the snapshot create request.

In some implementations, copy process 10 may track 402 how manysnapshots of a plurality of snapshots are referencing a given point intime copy. For example, and referring to the example implementation ofFIG. 6, an example table 600, pit_copy_reference_count, may beintroduced in control path to keep track of how many snapshots are usinga given PIT copy in data path. One PIT copy may have multiple referencesas it can be mapped to more than one snapshot instance. Snapshotinstances may have distinct characteristics such as, e.g., snapshotname, retention periods, rule information, etc. The reference count maydrop as the snapshot instances are deleted either by the user or by asnapshot aging service of copy process 10. The PIT copy in data path maystay until all the snapshots are deleted, i.e., the reference count isdropped to 0.

The pit_copy_reference_count table may have the following example andnon-limiting attributes:

pit_copy_id: The unique id of PIT copy stored in data path.

reference_count: How many control path snapshots are mapped to this PITcopy.

In some implementations, copy process 10 may determine 404 a desiredexecuting time for the at least one snapshot request in the snapshotqueue, which, in some implementations, the desired execution time may bebased upon, at least in part, a storage object ID and a pacing window.For instance, when first considering an example without deduplication,an example algorithm may be used to calculate the execution time basedon the storage object id and a pacing window. This may guarantee thepacing will be uniform and consistent for any given storage object. Whena snapshot request is submitted into the system, the requester currentlypresents the globally unique object id for which the snapshot needs tobe taken. Additional attributes such as the name of the snapshot, and anoptional expiration time when the snapshot needs to be deleted may alsobe presented. This interface is enhanced so that the requester (e.g.,via copy process 10) may present a time window, in seconds, within whichthe snapshot request needs to be executed.

When a snapshot request is originated from a rule, the time window maybe set to an appropriate value based on the frequency setting in therule. For example, if the snapshot frequency is five minutes or less,the time window offered is equal to the frequency. For largerfrequencies (e.g., 15 minutes, 1 hour, etc.), the time window may be setto a fixed value of, e.g., five minutes.

A snapshot request arriving in the system may be first added to thesnapshot request queue, as noted above. When adding a snapshot requestto the queue, a targeted execution time may be determined 404 for therequest as an offset from the submission time. An example andnon-limiting algorithm of copy process 10 for generating the executiontime is as follows, however, it will be appreciated that varyingalgorithms may be used:

A cryptographic hash is generated based on the object id.

A modulo operation is performed on the hash to generate an offsetbetween 0 and time window.

The execution time is computed by adding the offset to the submissiontime.

For instance, the hashing function and the modulo operation ensures thatfor a given object id and a given time window, the same offset is alwaysgenerated. For example, if a scheduled snapshot request arrives at00:00:00 (HH:MM:SS) for an object with globally unique id of1234-1234-1234-1234-1234, and the time window is 300 (five minutes),assume the resulting hash value is 23526. The modulo operation, 23526%300, would result in an offset of, e.g., 126 (seconds). Therefore, theexecution time for the request is set to 00:02:06. A subsequent requestarriving at 00:05:00 for the same object with the same window would haveits execution time set to 00:07:06, thereby ensuring a five minutedifferential in the execution time.

If a five minute snapshot rule triggered snapshot requests for 1000objects with distinct globally unique ids at 00:00:00, the executiontime for the 1000 requests would be distributed between 00:00:00 and00:05:00.Mathematically: Execution Time=Submission Time+Offset, whereOffset=hash(storage_object_id) % Time Window.

Next, consider the case with deduplication. When a snapshot request issubmitted for an object that already has one or more pending requestssubmitted to the queue (e.g., from other rule(s)), the execution timefor the new request may be first computed using the above method. If theexecution time for the new request is earlier than the execution timefor the pending requests, then the execution time for all the pendingrequests for the object may be set to the new execution time. Otherwise,the execution time of the new request may be set to the execution of anexisting request (note in some implementations that all existingrequests for the same object should have the same execution time).

In some implementations, copy process 10 may dequeue 406 the at leastone snapshot request, where, in some implementations, the dequeuing 406may be based upon, at least in part, a centralized timer, and/or atleast one of an executing time of at least one request being less thanor equal to a current time and a duplicate request for a same storageobject. For example, a centralized timer-based process of copy process10 may be introduced to submit requests for PIT copy creation/dequeuingthe snapshot request queue. This process may run frequently and executesmall chunks of requests with each run, and/or, in some implementations,the process (e.g., via copy process 10) may deduplicate 408 duplicaterequests in the snapshot queue (e.g., deduplicate multiple requestsagainst the same object). For example, the entries in the snapshotrequest queue may be dequeued based on a timer. When the dequeuingprocess of copy process 10 kicks in, it may retrieve all qualifiedsnapshot requests—all requests with execution time less than or equal tocurrent time and any duplicate requests for the same object may beserved. The retrieved, deduplicated requests may then be batched andsent to the data path for execution. Once the data path processing issuccessfully completed, a response may be sent with the data pathspecific information for the PIT copies created. The above-notedpit_copy_reference_count table may be populated with the PIT copiescreated, one per object, and the reference count attribute may be set tothe number of concurrent requests processed for the object. Eachcompleted request may then be populated in the snapshot table. Therequests may then be removed from the queue.

An example dequeuing process 700 of copy process 10 is shown in theexample implementation of FIG. 7. As shown in FIG. 7, the timer fordequeuing snapshot requests is triggered 701 by the system (e.g., viacopy process 10). It starts the dequeuing process. Dequeuing process 700may query 702 the snapshot request queue for qualified requests. All therequests that have the execution time set before the current time asqualified is considered, in other words, execution time<=current time.The snapshot request queue may return 703 all the qualified requests todequeuing process 700. Dequeuing process 700 may send 704 all thequalified snapshot requests to PIT Copy Creation Request Handler. PITcopy request handler (e.g., via copy process 10) may deduplicate therequests. In some implementations, the PIT copy may be mapped to (andreference counted by) at least a portion of the plurality of snapshots.For example, when there is more than one request for creating PIT copyfor the same storage object, only one PIT copy creation request to besent to data path may be included. PIT copy request handler may send 705the request to create PIT copies in the data path. Data path (e.g., viacopy process 10) may create 706 PIT copies and send the response withPIT copy id, PIT copy source time, etc., to PIT copy response handler.PIT copy response handler may send 707 the mapping of the storage objectid and PIT copy id back to the dequeuing process. The dequeuing processmay create 708 the end user facing snapshot instances based for eachqualified snapshot request using the PIT copy id and other parameters inthe request. The dequeuing process may create 709 an entry for each PITcopy in the PIT copy reference count table to record how many userfacing snapshots are referencing this PIT copy. The dequeuing processmay clear 710 the executed qualified requests from the queue whether ornot the PIT copy creation is successful or not.

In some implementations, copy process 10 may delete 410 an entry of theat least one snapshot request, and in some implementations, copy process10 may decrement 412 a reference count from a reference count table. Putanother way, copy process 10 may delete snapshot requests after theyhave been dequeued and served by the system, and the reference count maybe decreased only when the snapshot itself is deleted. When a newsnapshot is created, the reference count that references how manysnapshots are using PIT may be increased. For example, when a snapshotdelete request is submitted, the snapshot entry may be deleted from thesnapshot table, and the reference_count may be decremented from thecorresponding pit_copy_reference_count table. If the reference_countgoes to zero, then the entry may be removed from thepit_copy_reference_count table, and an actual PIT copy delete requestmay be submitted to the data path.

The terminology used herein is for the purpose of describing particularimplementations only and is not intended to be limiting of thedisclosure. As used herein, the singular forms “a”, “an” and “the” areintended to include the plural forms as well, unless the context clearlyindicates otherwise. As used herein, the language “at least one of A, B,and C” (and the like) should be interpreted as covering only A, only B,only C, or any combination of the three, unless the context clearlyindicates otherwise. It will be further understood that the terms“comprises” and/or “comprising,” when used in this specification,specify the presence of stated features, integers, steps (notnecessarily in a particular order), operations, elements, and/orcomponents, but do not preclude the presence or addition of one or moreother features, integers, steps (not necessarily in a particular order),operations, elements, components, and/or groups thereof.

The corresponding structures, materials, acts, and equivalents (e.g., ofall means or step plus function elements) that may be in the claimsbelow are intended to include any structure, material, or act forperforming the function in combination with other claimed elements asspecifically claimed. The description of the present disclosure has beenpresented for purposes of illustration and description, but is notintended to be exhaustive or limited to the disclosure in the formdisclosed. Many modifications, variations, substitutions, and anycombinations thereof will be apparent to those of ordinary skill in theart without departing from the scope and spirit of the disclosure. Theimplementation(s) were chosen and described in order to explain theprinciples of the disclosure and the practical application, and toenable others of ordinary skill in the art to understand the disclosurefor various implementation(s) with various modifications and/or anycombinations of implementation(s) as are suited to the particular usecontemplated.

Having thus described the disclosure of the present application indetail and by reference to implementation(s) thereof, it will beapparent that modifications, variations, and any combinations ofimplementation(s) (including any modifications, variations,substitutions, and combinations thereof) are possible without departingfrom the scope of the disclosure defined in the appended claims.

What is claimed is:
 1. A computer-implemented method comprising:submitting, by a computing device, at least one snapshot request of aplurality of snapshots requests into a snapshot queue; tracking how manysnapshots of a plurality of snapshots are referencing a given point intime copy, wherein the given point in time copy is mapped to at least aportion of the plurality of snapshots; determining a desired executingtime for the at least one snapshot request in the snapshot queue;dequeuing the at least one snapshot request; and deduplicating duplicaterequests in the snapshot queue.
 2. The computer-implemented method ofclaim 1, wherein the dequeuing is based upon, at least in part, acentralized timer.
 3. The computer-implemented method of claim 1,wherein the dequeuing is based upon, at least in part, at least one ofan executing time of the at least one request being less than or equalto a current time and a duplicate request for a same storage object. 4.The computer-implemented method of claim 1, wherein the desiredexecution time is based upon, at least in part, a storage object ID anda pacing window.
 5. The computer-implemented method of claim 3, furthercomprising deleting an entry of the at least one snapshot request. 6.The computer-implemented method of claim 5, further comprisingdecrementing a reference count from a reference count table.
 7. Acomputer program product residing on a computer readable storage mediumhaving a plurality of instructions stored thereon which, when executedacross one or more processors, causes at least a portion of the one ormore processors to perform operations comprising: submitting at leastone snapshot request of a plurality of snapshots requests into asnapshot queue; tracking how many snapshots of a plurality of snapshotsare referencing a given point in time copy, wherein the given point intime copy is mapped to at least a portion of the plurality of snapshots;determining a desired executing time for the at least one snapshotrequest in the snapshot queue; and dequeuing the at least one snapshotrequest, wherein the dequeuing is based upon, at least in part, acentralized timer.
 8. The computer program product of claim 7, whereinthe operations further comprise deduplicating duplicate requests in thesnapshot queue.
 9. The computer program product of claim 7, wherein thedequeuing is based upon, at least in part, at least one of an executingtime of the at least one request being less than or equal to a currenttime and a duplicate request for a same storage object.
 10. The computerprogram product of claim 7, wherein the desired execution time is basedupon, at least in part, a storage object ID and a pacing window.
 11. Thecomputer program product of claim 9, wherein the operations furthercomprise deleting an entry of a snapshot associated with the at leastone snapshot request.
 12. The computer program product of claim 11,wherein the operations further comprise decrementing a reference countfrom a reference count table.
 13. A computing system including one ormore processors and one or more memories configured to performoperations comprising: submitting at least one snapshot request of aplurality of snapshots requests into a snapshot queue; tracking how manysnapshots of a plurality of snapshots are referencing a given point intime copy, wherein the given point in time copy is mapped to at least aportion of the plurality of snapshots; determining a desired executingtime for the at least one snapshot request in the snapshot queue; anddequeuing the at least one snapshot request, wherein the dequeuing isbased upon, at least in part, at least one of an executing time of theat least one request being less than or equal to a current time and aduplicate request for a same storage object.
 14. The computing system ofclaim 13, wherein the dequeuing is based upon, at least in part, acentralized timer.
 15. The computing system of claim 13, wherein theoperations further comprise deduplicating duplicate requests in thesnapshot queue.
 16. The computing system of claim 13, wherein thedesired execution time is based upon, at least in part, a storage objectID and a pacing window.
 17. The computing system of claim 13, whereinthe operations further comprise deleting an entry of a snapshotassociated with the at least one snapshot request and decrementing areference count from a reference count table.